He's changed since he came back — he seems positively cheerful...是什么意思？

He's changed since he came back — he seems positively cheerful...

他回来后变了个样，看起来确实很高兴。

changed

[医]变化的，改变的；

例句
Since the Sixties, afforestation has changed the Welsh countryside.
60年代以来，植树造林已经改变了威尔士的乡村面貌。

since

prep. 从…以来，自从…之后，自从；adv. 以后，此后，后来，（距今几年）以前，（从那时候起几年）以前；conj. 自从…以来，自从…的时候起，既然，因为；

例句
Janet had been abused by her father since she was eleven.
珍妮特从11岁起就遭受父亲虐待。

he

pron. 他，它，一个人；n. 雄性动物；

例句
Logic had prevailed and he had abandoned the idea.
最终理智占了上风，他打消了那个念头。

came

v. 来( come的过去式 )，到达，达到（认识、理解或相信的程度），出生；

例句
She came in for a coffee, and told me about her friend Shona...
她进来喝了杯咖啡，并向我谈起了她的朋友肖纳。

back

n. 背，背部，背面，反面，后面，后部，（椅子等的）靠

例句
He looked back at the abject, silent girl and repeated his question.
他转过头看着这个噤若寒蝉的女孩，又重复了一遍他的问题。

seems

v. 好像，仿佛（ seem的第三人称单数 ）；

例句
Almost like an accident of nature, this family has produced more talent than seems possible.
就像是天缘巧合，这个家族不可思议地人才辈出。

positively

adv. 明确地，断然地，肯定地；

例句
The bathroom, with its ancient facilities, is positively arctic.
该浴室设备陈旧，肯定非常寒冷。

cheerful

adj. 欢乐的，高兴的，令人愉快的；

例句
Smiles, nods, and cheerful faces added to the general gaiety.
微笑、点头和喜洋洋的脸庞使喜庆的气氛变得更浓了。